Montserrat Figueras: Soprano celebrated for her mastery of pre-Baroque music

One evening in 1988 my girlfriend and I were driving home from work when one of the most exquisite sounds I had heard emerged from the car radio.

I asked her to pull in at the side of the road so I could pay more attention. It was obviously something medieval: a drone below a slow-moving chordal choral texture above which a dazzlingly clear soprano voice spun a line of the purest silk, as strong as it was delicate. That voice belonged to the Catalan soprano Montserrat Figueras, in a new recording, El Cant de la Sibilla, three sibylline chants – Latin, Provençal and Catalan – recorded with her husband, Jordi Savall, and the early-music group they had recently founded, La Capella Reial de Catalunya.

What made Figueras' voice so compelling was its uncanny blend of purity and power, of innocence and authority. She was also a prolific recording artist, singing music from the Middle Ages to the Classical period – a longer stretch of time than from then to the present day; the early focus was the music of Spain, but soon expanded to take in most of mainland Europe and latterly stretched to the Middle East. The unusual ambit and number of those recordings made her the pre-eminent singer of pre-Baroque music for three decades.

Figueras was born into a musical family and began to study singing as a girl, intending to become an actress. Together with her sister Pilar, who has also made a number of striking recordings of medieval music, she paid especial attention to early vocal techniques. Joining a local choir, Aleluya, she graduated from there to an early-music group, Ars Musicae de Barcelona, with which Victoria de los Angeles had made her earliest surviving recording.

Figueras and Savall had already encountered each other, as Savall later recalled: "We met in cello class, when we were both studying cello around the age of 22 or 23. My teacher was not very comfortable with the way I played Bach. Montserrat would remain behind, listening from the hallway. When I'd leave the class, she'd always say to me very softly, 'Don't worry. You play very well'. This was a fantastic feeling that lasted the whole day."

A little later, Enric Gispert, the conductor of Ars Musicae, asked Figueras if she knew a good viola da gamba player for another Los Angeles recording that was on the horizon. Figueras wondered if Savall, already a fine cellist, might be interested, and so they both took part in the recording. This first encounter with Figueras' voice, Savall said, was "the beginning of everything".

They moved together to Basel to study at the Music Academy and Schola Cantorum Basiliensis, then the nub of the burgeoning early-music movement, and in 1968 they were wed. In their 43 years of marriage neither seemed to age much; Figueras especially retained a schoolgirl freshness that belied her age.

In 1974, together with the Argentinian bassoonist Lorenzo Alpert and American lutenist Hopkinson Smith, Savall and Figueras set up the first of their early-music consorts, Hespèrion XX, "Hesperion" being a Greek word referring to both Spain and Italy, and "XX" to site the group in the 20th century (keeping up with the times, it was renamed Hespèrion XXI in 2000). Hespèrion XX was a viol-based group, and so it was followed in 1987 by La Capella Reial de Catalunya to allow the performance of vocal music. A third group, Le Concert des Nations, followed two years later; it provided La Capella Reial with a specialist period-instrument orchestra. Each ensemble expanded the music accessible for performance, so that Figueras, Savall and their fellow musicians could eventually reach as far as opera, the mid-19th century and the music of Turkey.

A logical extension was the foundation of their own CD label, Alia Vox, in 1998. Their releases became a byword for freshness and fidelity, with recorded sound that was both immediate and warm; the recording schedule was buttressed by extensive international concertizing. The versatility of Figueras' voice was an important element in their success: whether she was singing a formal operatic aria or a simple lullaby, Figueras invested it with dignity and an essential honesty.

In a newspaper interview in 2006 Savall explained the improbable popularity of what had hitherto been a specialist activity. "Montserrat and I, we are from our time and we have our own experience and sensitivity. [But] The way we say 'I love you' has not changed through thousands of years ... The essential things in life, there is no change".

The quality of Figueras' work was acknowledged in 2003 when she was made an Officier of the Ordre des Arts et des Lettres by the French government, and earlier this year the government of Catalonia bestowed on her its highest civilian award, the Cross of St Jordi. By then she was already struggling against the cancer that would eventually take her life, but she carried on making music. Her last concert appearance was in August, and her last recording, La Sublime Porte: Voix d'Istanbul, 1430–1750 – with, of course, her husband and Hespèrion XXI – was released only a month before she died.

Montserrat Figueras García, singer: born Barcelona 15 March 1942; married 1968 Jordi Savall (one son, one daughter); died Cerdanyola del Vallès, Spain 23 November 2011